Method for producing a foam body having an internal structure

ABSTRACT

A method for producing a foam body ( 10 ) having an internal structure ( 100, 200, 300 ), comprising the steps: I) selecting an internal structure ( 100, 200, 300 ) to be formed in the foam body ( 10 ), the structure comprising a first polymer material; II) providing a foam body ( 10 ), the foam body ( 10 ) comprising a second polymer material which is different to the first polymer material; III) injecting, by means of an injection means ( 20 ), a predefined amount of a melt of the first polymer material or a predefined amount of a reaction mixture ( 30, 31, 32 ) which reacts to form the first polymer material at a predefined location inside the foam body ( 10 ), corresponding to a volume element of the internal structure ( 100, 200, 300 ); IV) repeating step III) for further predefined locations inside the foam body ( 10 ), corresponding to further volume elements of the internal structure ( 10 ), until the internal structure ( 10 ) is formed. The invention also relates to a foam body ( 10 ) which has an internal structure ( 100, 200, 300 ) and is obtainable by the method according to the invention.

The present invention relates to a process for producing a foam bodyhaving an internal structure, comprising injection by means of aninjection means of a predetermined amount of a melt of a polymericmaterial or a predetermined amount of a reaction mixture which reacts toafford a polymeric material into a predetermined location of a foam bodywhich corresponds to a volume element of the internal structure. Theinvention likewise relates to a foam body having an internal structureobtainable by the process according to the invention.

The modification of foams by introduction of other materials into thefoam is known per se. The modification may be for example a repair, amechanical reinforcement, an altering of damping characteristics or animprovement in combustion behavior.

DE 20 2010 014376 U1 is concerned with plastics sandwich materialtechnology and has for its object to provide a composite material and anarrangement with the composite material with which a light and stablesupport structure is achieved. Disclosed is a composite material havinga three-dimensional sponge structure, in particular a sponge material orsponge-like material, and a connecting material which binds and/orstabilizes the sponge structure. The connecting material may be orcomprise a plastics material, in particular a resin material, inparticular polyester resin or epoxy resin.

WO 2012/148915 A2 relates to the field of cushioning materials anddiscloses a cushioning element comprising a breathable porous foamcomprising an array of interconnected cell walls, thus defining anopen-pored network, and comprising an elastomeric material which isformed over at least a portion of the interconnected cell walls. Theelastomeric material comprises an elastomeric polymer and a plasticizer,wherein a weight ratio of plasticizer to elastomeric polymer is 0.1 to50. The breathable porous foam is adapted to allow gases passage throughat least one portion of the open-pored network adjacent to theelastomeric material.

WO 03/020504 A1 describes a process for producing a polyolefin-infusedporous material, comprising: (a) mixing an olefin monomer resinformulation with a metathesis catalyst to obtain a catalyzed resinformulation; (b) infusing the mixture into a porous material, whereinthe porous material is selected from the group consisting of wood,cement, concrete, open-celled and reticulated foams and sponges, papers,cardboards, felts, ropes or braids of natural or synthetic fibers andsintered materials; the mixture penetrates the pores of the porousmaterial; (c) curing the catalysed resin formulation inside the porousmaterial.

EP 2 886 302 A2 relates to the shaping and the production of reinforcingelements which pass through the thickness of the sandwich structure forreinforcement of sandwich structures. The process for producingreinforced sandwich structures disclosed there comprises the steps of:introducing a pin into a foamed or filled honeycomb core material,wherein the pin and the core material contain a thermoplastic or amixture of thermoplastics and the pin is heated such that the corematerial softens or melts upon introduction of the pin at theintroduction point; and/or the core material is heated at theintroduction point so that the core material softens or melts.

WO 2015/066528 A1 discloses a composite material having a modulus ofelasticity of less than 0.1 MPa at 100% elongation comprising a polymermatrix and a non-Newtonian fluid. The composite material may be employedin shock and impact absorption applications in order to reduce initialaccelerative forces and accelerative forces brought about by shockwaves.

Most prior art processes for modifying foams are rather unspecific andare not suitable for the construction of complex structures inside thefoam. It would therefore be a requirement that the complex structure beprovided first and then overfoamed. Thus WO 87/01775 A1 discloses aspring element having at least two main parts and an array of shockabsorbing curved elements which extend between the main parts and areintegrally secured thereto by insert molding. The aforementioned mainparts are in the form of cut-to-length hollow profiles having a numberof openings for receiving the curved elements, wherein the curvedelements have a diameter which is smaller than that of theaforementioned openings in order that elements may be arranged in theaforementioned openings at a desired predetermined angle. The cavity ofthe profiles is filled with a molding material. The aforementionedspring element may be embedded in a foam, preferably a polyurethane foamor polyethylene foam.

The embedding in a foam necessitates access to foaming plants with allof their capital and safety requirements. In order, given the ascendingreaction mixture resulting in a foam, to achieve a predeterminedorientation of the structures in the finished foam, said structures mustbe secured. Such securing elements would then extend as far as the outersurface of the foam which may be unwanted for mechanical and aestheticreasons. A further aspect is that in overfoaming of closed structuresthe cavities of the structures cannot be filled by the foam.

It would be desirable for the production of foams functionalized withspecific internal structures if stock foams could be purchased andsubsequently functionalized. The present invention accordingly has forits object to provide such a process for producing a foam body having aninternal structure.

The problem is solved in accordance with the invention by a process asclaimed in claim 1. A foam body obtainable by the process according tothe invention and having an internal structure forms the subject matterof claim 15. Advantageous developments are specified in the subsidiaryclaims.

A process according to the invention for producing a foam body having aninternal structure comprises the steps of:

-   I) selecting an internal structure to be formed in the foam body,    wherein the structure comprises a first polymeric material;-   II) providing a foam body, wherein the foam body comprises a second    polymeric material distinct from the first polymeric material;-   III) injecting by means of an injection means a predetermined amount    of a melt of the first polymeric material or a predetermined amount    of a reaction mixture which reacts to afford the first polymeric    material at a predetermined location inside the foam body which    corresponds to a volume element of the internal structure;-   IV) repeating step III) for further predetermined locations inside    the foam body corresponding to further volume elements of the    internal structure until the internal structure is formed.

A foam body having an internal structure obtainable by a processaccording to the invention, wherein the internal structure comprises afirst polymeric material and the foam body comprises a second polymericmaterial and the material of the internal structure is distinct from thematerial of the foam body has the features that all surfaces of theinternal structure contact the foam body, that the internal structure isa spring having a loading direction and that upon loading of the foambody at a location at which the internal structure is present and alongthe loading direction of the internal structure the determinedcompressive strength (40% compression, DIN EN ISO 3386-1:2010-09) is≥10% to ≤10 000% higher than the compressive strength (40% compression,DIN EN ISO 3386-1:2010-09) of the foam body at a location at which nointernal structure is present.

The present invention is in particular suitable for the modification offlexible foam bodies, such as are used in mattresses or cushioningelements. Multizone flexible foam bodies are complex and costly toproduce since different foams and inserts require adhesive bonding toone another in a plurality of operations. In addition, these productionprocesses provide only limited options for individual adaptation topersons or objects.

Compared to conventional processes the process according to theinvention makes it possible to produce products such as multizonemattresses in a simpler and more cost-effective fashion since numerousprocess steps are integrated into a single step. Further functionalitiesmay be integrated into foam objects which can also be individuallyadapted with little additional complexity through the use of digitalmanufacturing processes.

Injected patterns and structures make it possible to determine thecharacteristics of foams upon application of force so that onlypredefined deformations are allowed. It is further possible to useinjected patterns to mark the foam in such a way as to impedecounterfeiting.

This process thus makes it possible to achieve cost savings and processimprovements for already established (flexible) foam applications aswell as injection of complex and individualized shapes which unlocktotally novel fields of application for the use of flexible foams.

Step (I) of the process according to the invention comprises selectingan internal structure to be formed in the foam body. This selecting isadvantageously carried out in a CAD program which provides athree-dimensional model of the structure and in this three-dimensionalmodel subdivides the structure into individual volume elements.

The internal structure may for example have a length of ≥0.1 mm to ≤5000cm, preferably ≥0.5 mm to ≤1000 cm, more preferably ≥1 cm to ≤100 cm.

One example of such a structure to be formed in the foam body is a coilspring. Such coil springs may for example be provided in mattresses orcushions in order locally to form regions having an elevated compressivestrength. Further examples of suitable structures include those whichfacilitate securing of the foam body. In the simplest case these may besolid volumes into which for example threads for receiving a screwconnection are subsequently cut.

According to the invention it is provided that the internal structure tobe formed comprises a first polymeric material. Suitable materialsinclude for example thermoplastically processable plastics formulationsbased on polyamides, polyurethanes, polyesters, polyethers, polyimides,polyether ketones, polycarbonates, polyacrylates, polyolefins, polyvinylchloride, polyoxymethylene and/or crosslinked materials based onpolyepoxides, polyurethanes, polysilicones, polyacrylates, polyesters,rubber materials and mixtures and mixed polymers thereof.

The first polymeric material may be in the form of a solid or a foam.When the first polymeric material is a foam, weight savings may berealized.

Particularly suitable as the first polymeric material according to oneaspect of the invention are thermoplastic elastomers (TPE),thermoplastic polyurethane (TPU), polycarbonate (PC), polyamide (PA),polyethylene terephthalate (PET), polybutylene terephthalate (PBT),cycloolefinic copolyester (COC), polyether ether ketone (PEEK),polyether amide ketone (PEAK), polyetherimide (PEI), polyimide (PI),polypropylene (PP) or polyethylene (PE), acrylonitrile butadiene styrene(ABS), polylactate (PLA), polymethyl methacrylate (PMMA), polystyrene(PS), polyvinyl chloride (PVC), polyoxymethylene (POM),polyacrylonitrile (PAN), polyacrylate or celluloid. TPU or PC arepreferred.

Particularly suitable for construction of the first polymeric materialaccording to a further aspect of the invention are chemically curable 2Kpolyurethane, 2K epoxide or moisture curable polyurethane systems, aircurable or free-radically curable unsaturated polyesters or UV curablereactive resins, for example based on vinyl and acryloyl compounds, suchas are described inter alia in EP 2 930 009 A2 and DE 10 2015100 816.

Step (II) of the process comprises providing a foam body, wherein thefoam body comprises a second polymeric material distinct from the firstpolymeric material. This may also be for example a thermoplastic foam, apolyurethane resin foam, an epoxy resin foam, a polyester resin foam, arubber foam, an acrylate resin foam or a polyolefin resin foam. It ispossible for the internal structure and the foam body to comprise amaterial from the same substance class, the materials per senevertheless being chemically distinct. One example is a foam body madeof a flexible polyurethane foam and a structure made of an elastomericpolyurethane. The distinctness of the polymeric materials may alsomanifest in a distinctness of at least one physical property. Forexample the first polymeric material may be a polymer foam obtained fromthe same synthesis components as the foam of the second polymericmaterial but having a different density.

Step (III) of the process comprises injecting by means of an injectionmeans a predetermined amount of a melt of the first polymeric materialor a predetermined amount of a reaction mixture which reacts to affordthe first polymeric material at a predetermined location inside the foambody. One example of an injection means is a cannula. Suitable internaldiameters may be in the range from ≥50 μm to ≤5 mm, preferably ≥100 μmto ≤4 mm, more preferably ≥500 μm to ≤2.5 mm.

In the case of a thermoplastic polymer a melt of the polymer isinjected. However, it is also possible to employ reactive resins asone-component or multicomponent systems in which a reaction mixturereacts to afford the desired polymeric material. The reaction mixturemay be injected through the cannula in ready-mixed form or else be mixedonly in the foam body through use of a cannula having a plurality ofconduits for example.

The material for a volume element of the to-be-constructed internalstructure provided for injection may be injected continuously ordiscontinuously. Depending on the nature of the foam the injectedmaterial may bring about local destruction of the foam and supplant thefoam or else may displace the foam.

In the process according to the invention the material is preferably notinjected into cavities that are already present in the foam andcorrespond to the shape of the volume element or the internal structure.This is an advantage of the process according to the invention since theupstream steps for providing the cavities to be filled are omitted. Anopen-celled or closed-celled foam unmodified in respect of its internalstructure may be employed.

The injected quantity of material is supported by the surrounding formof the foam body and can therefore remain in the location intendedtherefor. The injected quantity of material corresponds, also in termsof its situation in the foam body, to a volume element of the internalstructure to be formed. In contrast to layerwise additive manufacturingprocesses such as SLS or FDM the process according to the invention isnot limited to layerwise construction of the structure but rather, onaccount of the supporting action of the foam, allows for much freerpositioning of the material for the structure.

During injection in step III) the injection means may be stationary orin motion relative to the foam body. When the injection means is inmotion, larger volume elements per injection operation may beconstructed. It is preferable when the motion of the injection means isopposed to the direction of motion in which the injection means haspenetrated into the foam body.

After the injection in step III) an injection channel brought about bythe injection means in the foam may be sealed again. This may beachieved by introducing into the injection channel an adhesive or areaction mixture which reacts to afford a polymer foam. This ispreferably a reaction mixture which reacts to afford the polymer of thesecond polymeric material with or without blowing agent.

The injection in step III) is preferably performed using a multiaxialrobot such as a 6-axis robot. Thus a 6-axis robot arm can move aninjection means according to paths previously generated on a computerand inject patterns and shapes into the foam body.

The path of the injection in step III) is not limited to a particularspatial direction. It is possible for the individual injections to becarried out from very different directions. When the injection means isa cannula this means that the foam body is punctured uniformly so thatlocal accumulation of parallel penetration channels and thus localweakening or destruction of the foam is avoided. However, it is alsopossible that a local weakening or destruction of the foam materialbrought about by puncturing of the foam body by the injection means isused as a constructive feature for the foam body having an internalstructure.

According to the instruction in step IV) of the process the injectionstep III) is repeated at further predetermined locations inside the foambody so that further volume elements of the internal structure to beformed are reproduced in the foam body by material injection. This iscarried out until the target structure has been formed.

The internal structure may for example bring about a subtle or markedhaptic alteration of the properties of the modified foam body whichmanifests for example in the form of altered damping characteristics,surface roughness or foam surface structure under stress. One example isthe injection of small volume bodies of a material having a higherdensity than the foam directly below the foam surface which can resultin an improvement in air circulation in the foam surface under stress.

The process according to the invention is capable of elevating thedensity of the foam body in a spatially specific fashion but based intotal on the foam volume for example by >0.5% to <1000%.

Preferred embodiments of the invention are described hereinbelow. Theymay be combined with one another as desired unless the opposite is clearfrom the context.

In a preferred embodiment of the process the injected melts or theinjected reaction mixtures become at least partially interconnected toafford a common volume element in two consecutive steps III). In thecase of injection of a polymer melt the fact that the foam body acts asa thermal insulation means may be utilized. This facilitates thecoalescing of the polymer melt injected in the individual injectionsteps.

In a further preferred embodiment of the process a plurality ofdifferent first polymeric materials are employed. For example 2, 3, 4 or5 different first polymeric materials may be employed in the processaccording to the invention and these may also be injected by differentmeans of application (polymer melt/reaction mixture). The differentfirst polymeric materials may be compatible with one another which meansthat they can enter into a positive connection with one another.However, they may also be intentionally incompatible with one anotherwhen for example parts of a structure movable relative to one anotherare to be constructed.

In a further preferred embodiment of the process a plurality ofdifferent injection means are employed. The number of differentinjection means is in principle limited only by the geometry of the foambody and the space requirements of the injection means.

In a further preferred embodiment of the process a plurality ofinjection means differing in their mechanical construction are employed.The number of different injection means is in principle limited only bythe geometry of the foam body and the space requirements of theinjection means. A distinguishing mechanical construction may forexample be constituted by different internal diameters of employedcannulas.

In a further preferred embodiment of the process the foam body comprisesa flexible foam having a compressive strength (40% compression, DIN ENISO 3386-1:2010-09) of ≥10 to ≤100 kPa and a density (DIN EN ISO 845) of≥10 kg/m³ to ≤100 kg/m³. Preference is given to compressive strengths inthe range from ≥20 to ≤80 kPa, more preferably ≥30 to ≤60 kPa. Preferreddensities are ≥20 kg/m³ to ≤80 kg/m³, more preferably ≥30 kg/m³ to ≤60kg/m³.

In a further preferred embodiment of the process the second polymericmaterial is a polyurethane polymer. It is preferable when the secondpolymeric material is a flexible polyurethane foam obtainable from areaction mixture comprising the components:

A1

-   A1.1 at least one polyether polyol having a functionality of 2 to 8,    preferably of 2 to 6, particularly preferably of 2 to 4, an OH    number according to DIN 53240 in a range from 20 to 70 mg KOH/g and    a polyoxypropylene (PO) content in an amount of 50% to 100% by    weight and a polyoxyethylene (EO) content in an amount of 0% to 50%    by weight,-   A1.2 optionally at least one polyether polyol having a hydroxyl    functionality of 2 to 8, preferably of 2 to 6, particularly    preferably of 2, a hydroxyl (OH) number according to DIN 53240 in a    range from 50 to 65 mg KOH/g and a PO content in an amount of 45% to    55% by weight and an EO content in an amount of 45% to 55% by    weight;-   A1.3 optionally at least one dispersion of a polymer in a polyether    polyol, wherein the OH number according to DIN 53240 of the    dispersion is in a range from 10 to 30 mg KOH/g and wherein the    polyether polyol has a hydroxyl functionality of 2 to 6, preferably    of 2 to 4, particularly preferably of 3, a PO content in an amount    of 70% to 90% by weight and an EO content in an amount of 10% to 30%    by weight;-   A1.4 optionally at least one polyether polyol having a functionality    of 2 to 8, preferably of 2 to 6, particularly preferably of 3, an OH    number in a range from 220 to 290 mg KOH/g and a PO content in an    amount of up to 25% by weight and an EO content in an amount of at    least 75% by weight;-   A2 water and/or physical blowing agent,-   A3 optionally compounds comprising isocyanate-reactive hydrogen    atoms and having an OH number of 140 mg KOH/g to 900 mg KOH/g,-   A4 assistant and additive substances such as catalysts,    surface-active additives, pigments or flame retardants and    Component B: Di- and/or Polyisocyanates, Preferably Diisocyanates.

The production of the flexible PUR foam is generally carried out at anNCO index of 70 to 130, preferably of 80 to 115, particularly preferablyof 85 to 95.

In a further preferred embodiment of the process the internal structureselected in step I) is adapted to alter the deformation behavior of thefoam body under tensile load, compressive load and/or shear load suchthat upon deformation under the load a volume element of the foam bodywhich encompasses the internal structure undergoes a change to a volumeof ≥10% (preferably ≥50%, more preferably ≥100%) relative to the volumeof a volume element of the foam body (10) which comprises no internalstructure (100). The change in volume under load may be simulated by FEMcalculation or else determined experimentally. For example in a foambody a volume element having the internal structure is compressible froma starting volume of 100 cm³ to 75 cm³ and a volume element withoutinternal structure is compressible from 100 cm³ to 50 cm³ under the samecompressive stress. After loading the volume of the volume elementhaving the internal structure is then 150% of the volume of the volumeelement without internal structure.

In a further preferred embodiment of the process the internal structureselected in step I) is a leaf spring, spiral torsion spring, ellipticalspring, parabolic spring, wave spring, leg spring, rod spring, coilspring, disk spring, a thread or a socket for bayonet mounts.

In a further preferred embodiment of the process the internal structureselected in step I) is a plurality of non-interconnected spherical,elliptical or rod-shaped volumes or a plurality of interconnectedspherical, elliptical or rod-shaped volumes. Spherical volumes may beachieved by injection of a material without moving the injection meansduring the injection operation. Similarly, rod-shaped volumes may beconstructed via a linear motion of the injection means during theinjection operation. The term “spherical” includes deviations from theideal sphere where the smallest distance and the largest distance of thesurface of the volume from the geometric midpoint of the volume differfrom one another by not more than 20%, preferably not more than 10%.

Rod-shaped volumes may be interconnected such that two volumes convergeat their ends and thus form a “V-shaped” entity. The angle between thelegs of the “V-shaped” entity may be 5° to 85°, preferably 15 to 60°. Itis also possible for more than two, for example 3 or four, rod-shapedvolumes to converge at a common point. The figure formed may bedescribed such that the rod-shaped volumes form at least some of theedges of a notional pyramid.

Rod-shaped volumes may also be interconnected such that a plurality ofthe volumes forms a network with node points. It is preferable when thenode points are distributed in a periodically repeating manner in atleast a portion of the volume of the body. If the node points aredistributed in a periodically repeating manner in a volume this may bedescribed using the terms of crystallography. The node points may bearranged according to the 14 Bravais lattices: simple cubic (sc),body-centered cubic (bcc), face-centered cubic (fcc), simple tetragonal,body-centered tetragonal, simple orthorhombic, base-centeredorthorhombic, body-centered orthorhombic, face-centered orthorhombic,simple hexagonal, rhombohedral, simple monoclinic, base-centeredmonoclinic and triclinic. The cubic lattices sc, fee and bec arepreferred.

Persisting with the crystallographic perspective the number ofrod-shaped volumes by means of which one node point is connected toother node points may be regarded as the coordination number of the nodepoint. The average number of rod-shaped volumes that emanate from thenode points may be ≥4 to ≤12 but it is also possible to achievecoordination numbers that are unusual or impossible in crystallography.

In a further preferred embodiment of the process the first polymericmaterial is a polyurethane polymer. This polyurethane polymer ispreferably obtained from a reaction mixture comprising the followingcomponents:

i) a polyisocyanate,

ii) optionally a polyisocyanate prepolymer

iii) a compound having at least two isocyanate-reactive groups,preferably hydroxyl groups.

Suitable as the polyisocyanate and component i) are, for example,1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI),isophorone diisocyanate (IPDI), 2,2,4- and/or2,4,4-trimethylhexamethylene diisocyanate, the isomericbis(4,4′-isocyanatocyclohexyl)methanes or mixtures thereof with anyisomer content, 1,4-cyclohexylene diisocyanate,4-isocyanatomethyl-1,8-octane diisocyanate (nonane triisocyanate),1,4-phenylene diisocyanate, 2,4- and/or 2,6-tolylene diisocyanate,1,5-naphthylene diisocyanate, 2,2′- and/or 2,4′- and/or4,4′-diphenylmethane diisocyanate, 1,3- and/or1,4-bis(2-isocyanatoprop-2-yl)benzene (TMXDI),1,3-bis(isocyanatomethyl)benzene (XDI), alkyl 2,6-diisocyanatohexanoates(lysine diisocyanates) having alkyl groups having 1 to 8 carbon atomsand mixtures thereof. Compounds which contain uretdione, isocyanurate,biuret, iminooxadiazinedione or oxadiazinetrione structures and arebased on the recited diisocyanates are also suitable building blocks ofcomponent i).

In one embodiment component i) may be a polyisocyanate or apolyisocyanate mixture having an average NCO functionality of 2 to 4with exclusively aliphatically or cycloaliphatically bonded isocyanategroups. Preferably concerned are polyisocyanates or polyisocyanatemixtures of the abovementioned type comprising uretdione, isocyanurate,biuret, iminooxadiazinedione or oxadiazinetrione structures and mixturesthereof and an average NCO functionality of the mixture of 2 to 4,preferably of 2 to 2.6 and particularly preferably of 2 to 2.4.

Employable with particular preference as component i) arepolyisocyanates based on hexamethylene diisocyanate, isophoronediisocyanate or the isomeric bis(4,4′-isocyanatocyclohexyl)methanes andmixtures of the abovementioned isocyanates.

The polyisocyanate prepolymers employable as component ii) areobtainable by reaction of one or more diisocyanates with one or morehydroxy-functional, in particular polymeric, polyols optionally withaddition of catalysts and auxiliary and additive substances. Alsoemployable in addition are components for chain extension, for examplewith primary and/or secondary amino groups (NH₂- and/or NH-functionalcomponents) for formation of the polyisocyanate prepolymer.

The polyisocyanate prepolymer as component ii) may preferably beobtainable from the reaction of polymeric polyols and aliphaticdiisocyanates. Preferred as component ii) are polyisocyanate prepolymersbased on polypropylene glycol as the polyol and hexamethylenediisocyanate as the aliphatic diisocyanate.

Hydroxy-functional polymeric polyols for conversion into thepolyisocyanate prepolymer B) may for example also be polyester polyols,polyacrylate polyols, polyurethane polyols, polycarbonate polyols,polyether polyols, polyester polyacrylate polyols, polyurethanepolyacrylate polyols, polyurethane polyester polyols, polyurethanepolyether polyols, polyurethane polycarbonate polyols and/or polyesterpolycarbonate polyols. These may be employed to produce thepolyisocyanate prepolymer individually or in any desired mixtures withone another.

Suitable polyester polyols for producing the polyisocyanate prepolymersii) may be polycondensates of di- and optionally tri- and tetraols andof di- and optionally tri- and tetracarboxylic acids orhydroxycarboxylic acids or lactones. Also employable for producing thepolyesters instead of the free polycarboxylic acids are thecorresponding polycarboxylic anhydrides or corresponding polycarboxylicesters of lower alcohols.

Examples of suitable diols include ethylene glycol, butylene glycol,diethylene glycol, triethylene glycol, polyalkylene glycols such aspolyethylene glycol and also 1,2-propanediol, 1,3-propanediol,1,3-butanediol, 1,4-butanediol, 1,6-hexanediol and isomers, neopentylglycol or neopentyl glycol hydroxypivalate or mixtures thereof, wherein1,6-hexanediol and isomers, 1,4-butanediol, neopentyl glycol andneopentyl glycol hydroxypivalate are preferred. Also employable arepolyols such as trimethylolpropane, glycerol, erythritol,pentaerythritol, trimethylolbenzene or trishydroxyethyl isocyanurate ormixtures thereof.

Employable dicarboxylic acids are phthalic acid, isophthalic acid,terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid,cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid,glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid,itaconic acid, malonic acid, suberic acid, 2-methylsuccinic acid,3,3-diethylglutaric acid and/or 2,2-dimethylsuccinic acid. Acid sourcesthat may be used further include the corresponding anhydrides.

Provided that the average functionality of the polyol to be esterifiedis ≥2, it is also possible to use monocarboxylic acids such as benzoicacid and hexanecarboxylic acid.

Preferred acids are aliphatic or aromatic acids of the abovementionedtype. Particularly preferred are adipic acid, isophthalic acid andphthalic acid.

Hydroxycarboxylic acids that may be co-used as reaction participants inthe production of a polyester polyol having terminal hydroxyl groups arefor example hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoicacid or hydroxystearic acid or mixtures thereof. Suitable lactones arecaprolactone, butyrolactone or homologs or mixtures thereof.Caprolactone is preferred.

Likewise employable for producing the polyisocyanate prepolymers ii) arehydroxyl-containing polycarbonates, for example polycarbonate polyols,preferably polycarbonate diols. For example these may have anumber-average molecular weight M_(n) of 400 g/mol to 8000 g/mol,preferably of 600 g/mol to 3000 g/mol. These are obtainable by reactionof carbonic acid derivatives, such as diphenyl carbonate, dimethylcarbonate or phosgene, with polyols, preferably diols.

Examples of diols suitable therefor are ethylene glycol, 1,2- and1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol,1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane,2-methyl-1,3-propanediol, 2,2,4-trimethylpentane-1,3-diol, dipropyleneglycol, polypropylene glycols, dibutylene glycol, polybutylene glycols,bisphenol A or lactone-modified diols of the abovementioned type ormixtures thereof.

The diol component preferably contains from 40 percent by weight to 100percent by weight of hexanediol, preferably 1,6-hexanediol and/orhexanediol derivatives. These hexanediol derivatives are based onhexanediol and may comprise not only terminal OH groups but also estergroups or ether groups. These derivatives are obtainable for example byreaction of hexanediol with excess caprolactone or by etherification ofhexanediol with itself to afford di- or trihexylene glycol. In thecontext of the present invention the amounts of these and othercomponents are selected in known fashion such that the sum does notexceed 100 percent by weight and in particular equals 100% by weight.

Hydroxyl-containing polycarbonates, in particular polycarbonate polyols,are preferably linear.

Polyether polyols are likewise employable for producing thepolyisocyanate prepolymers ii). Polytetramethylene glycol polyetherssuch as are obtainable by polymerization of tetrahydrofuran by cationicring opening are suitable for example. Likewise suitable polyetherpolyols may include adducts of styrene oxide, ethylene oxide, propyleneoxide, butylene oxide and/or epichlorohydrin onto di- or polyfunctionalstarter molecules. Employable suitable starter molecules include forexample water, butyl diglycol, glycerol, diethylene glycol,trimethylolpropane, propylene glycol, sorbitol, ethylenediamine,triethanolamine or 1,4-butanediol or mixtures thereof.

Preferred components for producing the polyisocyanate prepolymers ii)are polypropylene glycol, polytetramethylene glycol polyether andpolycarbonate polyols or mixtures thereof, wherein polypropylene glycolis particularly preferred.

Polymeric polyols having a number-average molecular weight M_(n) of 400g/mol to 8000 g/mol, preferably of 400 g/mol to 6000 g/mol andparticularly preferably of 600 g/mol to 3000 g/mol may be employed. Saidpolyols preferably have an OH functionality of 1.5 to 6, particularlypreferably of 1.8 to 3, very particularly preferably of 1.9 to 2.1.

The production of the polyisocyanate prepolymers ii) may employ not onlythe recited polymeric polyols but also short-chain polyols. Employableare for example ethylene glycol, diethylene glycol, triethylene glycol,1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butylene glycol,cyclohexanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, neopentylglycol, hydroquinone dihydroxyethyl ether, bisphenol A(2,2-bis(4-hydroxyphenyl)propane), hydrogenated bisphenol A(2,2-bis(4-hydroxycyclohexyl)propane), trimethylolpropane,trimethylolethane, glycerol or pentaerythritol or a mixture thereof.

Also suitable are esterdiols of the recited molecular weight range suchas α-hydroxybutyl ε-hydroxycaproate, ω-hydroxyhexyl γ-hydroxybutyrate,β-hydroxyethyl adipate or bis(β-hydroxyethyl) terephthalate.

Also employable for producing the polyisocyanate prepolymers ii) aremonofunctional isocyanate-reactive, hydroxyl-containing compounds.Examples of such monofunctional compounds are ethanol, n-butanol,ethylene glycol monobutyl ether, diethylene glycol monomethyl ether,diethylene glycol monobutyl ether, propylene glycol monomethyl ether,dipropylene glycol monomethyl ether, tripropylene glycol monomethylether, dipropylene glycol monopropyl ether, propylene glycol monobutylether, dipropylene glycol monobutyl ether, tripropylene glycol monobutylether, 2-ethylhexanol, 1-octanol, 1-dodecanol or 1-hexadecanol ormixtures thereof.

To produce the polyisocyanate prepolymers ii) diisocyanates maypreferably be reacted with the polyols at a ratio of isocyanate groupsto hydroxyl groups (NCO/OH ratio) of 2:1 to 20:1, for example of 8:1.This may form urethane and/or allophanate structures. A proportion ofunconverted polyisocyanates may subsequently be removed. This may becarried out for example using a thin-film distillation to obtain lowresidual monomer products having residual monomer contents of forexample ≤1 weight percent, preferably ≤0.5 weight percent, particularlypreferably ≤0.1 weight percent. The reaction temperature may be from 20°C. to 120° C., preferably from 60° C. to 100° C. Stabilizers such asbenzoyl chloride, isophthaloyl chloride, dibutyl phosphate,3-chloropropionic acid or methyl tosylate may be added duringproduction.

Also employable in addition for chain extension in the production of thepolyisocyanate prepolymers ii) are NH₂- and/or NH-functional components.

Suitable components for chain extension are organic di- or polyamines.Examples of employable compounds include ethylenediamine,1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane,1,6-diaminohexane, isophoronediamine, isomer mixture of 2,2,4- and2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine,diethylenetriamine, diaminodicyclohexylmethane ordimethylethylenediamine or mixtures thereof.

Also employable for producing the polyisocyanate prepolymers ii) arecompounds which comprise not only a primary amino group but alsosecondary amino groups or not only an amino group (primary or secondary)but also OH groups. Examples thereof are primary/secondary amines suchas diethanolamine, 3-amino-1-methylaminopropane,3-amino-1-ethylaminopropane, 3-amino-1-cyclohexylaminopropane,3-amino-1-methylaminobutane, alkanolamines such asN-aminoethylethanolamine, ethanolamine, 3-aminopropanol,neopentanolamine. For chain termination it is customary to use amineshaving an isocyanate-reactive group, for example methylamine,ethylamine, propylamine, butylamine, octylamine, laurylamine,stearylamine, isononyloxypropylamine, dimethylamine, diethylamine,dipropylamine, dibutylamine, N-methylaminopropylamine,diethyl(methyl)aminopropylamine, morpholine, piperidine, or suitablesubstituted derivatives thereof, amide amines formed from diprimaryamines and monocarboxylic acids, monoketime of diprimary amines,primary/tertiary amines, such as N,N-dimethylaminopropylamine.

The polyisocyanate prepolymers or mixtures thereof employed as componentii) may preferably have an average NCO functionality of 1.8 to 5,particularly preferably 2 to 3.5 and very particularly preferably 2 to2.5

Component iii) is a compound having at least two isocyanate-reactivehydroxyl groups. For example component iii) may be a polyamine or apolyol having at least two isocyanate-reactive hydroxyl groups.

Employable components iii) include hydroxy-functional, in particularpolymeric, polyols, for example polyether polyols. Polytetramethyleneglycol polyethers such as are obtainable by polymerization oftetrahydrofuran by cationic ring opening are suitable for example.Likewise suitable polyether polyols may include adducts of styreneoxide, ethylene oxide, propylene oxide, butylene oxide and/orepichlorohydrin onto di- or polyfunctional starter molecules. Employablesuitable starter molecules include for example water, butyl diglycol,glycerol, diethylene glycol, trimethylolpropane, propylene glycol,sorbitol, ethylenediamine, triethanolamine or 1,4-butanediol or mixturesthereof.

It is preferable when component iii) is a polymer having 2 to 4 hydroxylgroups per molecule, very particularly preferably a polypropylene glycolhaving 2 to 3 hydroxyl groups per molecule. It is preferable inaccordance with the invention when the polymeric polyols from C) have aparticularly narrow molecular weight distribution, i.e. a polydispersity(PD=M_(W)/M_(n)) of 1.0 to 1.5 and/or an OH-functionality of more than1.9. It is preferable when the recited polyether polyols have apolydispersity of 1.0 to 1.5 and an OH functionality of more than 1.9,particularly preferably not less than 1.95.

Such polyether polyols are obtainable in a manner known per se byalkoxylation of suitable starter molecules, in particular using doublemetal cyanide catalysts (DMC catalysis). This method is described forexample in patent specification U.S. Pat. No. 5,158,922 and in laid-openspecification EP 0 654 302 A1.

The reaction mixture for the polyurethane is obtainable by mixing thecomponents i), ii) and iii). The ratio of isocyanate-reactive hydroxylgroups to free isocyanate groups is preferably 1:1.5 to 1.5:1,particularly preferably from 1:1.02 to 1:0.95.

It is preferable when at least one of the components i), ii) or iii) hasa functionality of ≥2.0, preferably of ≥2.5 preferably of ≥3.0, in orderto introduce branching or crosslinking into the polymer element. Theterm “functionality” refers in the case of components i) and ii) to theaverage number of NCO groups per molecule and in the case of componentiii) to the average number of OH groups per molecule. This branching orcrosslinking brings about better mechanical properties and betterelastomeric properties, in particular better elongation properties.

The polyurethane may advantageously exhibit good mechanical strength andhigh elasticity. In particular the polyurethane may have a maximumstress of ≥0.2 MPa, in particular of 0.4 MPa to 50 MPa, and a maximumelongation of ≥250%, in particular of ≥350%. The polyurethane mayfurthermore exhibit a stress of 0.1 MPa to 1 MPa, for example of 0.1 MPato 0.8 MPa, in particular of 0.1 MPa to 0.3 MPa, in the workingelongation range of 50% to 200% (determination according to DIN 53504).The polyurethane may further exhibit a modulus of elasticity of 0.1 MPato 10 MPa, for example of 0.2 MPa to 5 MPa, at an elongation of 100%(determination according to DIN EN 150 672 1-1).

In addition to the components i), ii) und iii) the reaction mixture mayin addition also contain auxiliary and/or additive substances. Examplesof such auxiliary and additive substances are crosslinkers, thickeners,cosolvents, thixotropic agents, stabilizers, antioxidants, lightstabilizers, emulsifiers, surfactants, adhesives, plasticizers,hydrophobizing agents, pigments, fillers and flow control agents.

In a further preferred embodiment of the process a plurality of internalstructures of identical or different construction are formed in the foambody. For example a plurality of springs may be provided at certainregions of a mattress or a seat cushion.

In a further preferred embodiment of the process a plurality of stepsIII) are performed simultaneously. The construction of the desiredinternal structure is thus expedited if a plurality of injection meansare available.

In a further preferred embodiment of the process the predeterminedamount in step III) has a volume of ≥10 μL to ≤1000 mL. This volume ispreferably ≥50 μL to ≤50 mL, more preferably ≥100 μL to ≤5 mL.

In a further preferred embodiment of the process the injection means instep III) is a cannula, the end of the cannula is moved to thepredetermined location of the foam body for injection of thepredetermined amount and the movement of the end of the cannula isperformed such that first polymeric material already present in the foambody is not contacted by the cannula. This prevents the cannula fromdamaging the structure present in the construction.

In a further preferred embodiment of the process formation of theinternal structure is followed by performance of a material-removingaftertreatment step on the foam body having the internal structure. Thisis advantageous if the intended shape of the foam body is such thatlittle foam volume would be available to support the inner structurepresent in the construction. In this case a foam body having sufficientdimensions would initially be employed in the process according to theinvention and the end shape would subsequently be obtained via theaftertreatment step.

Articles advantageously producible by the process according to theinvention include for example shoe inserts, shoe soles, protectors,backpacks, cushioning elements, baby mats, orthopedic seat cushions,connecting elements, office chair seat bases, transit protectionarticles, inserts for containers, cosmetic sponges, neck-supportingpillows, mattresses, pillows, cleaning sponges, robotic grippers, soundabsorbers, sound-insulated stair treads, neck braces, plaster and railsystems, cushioning pads for training apparatus, sports mats, apparatusgrips, bicycle seats, car seats and/or seating furniture. Details arespecified in the following table without being limited thereto:

Product Examples/comments Shoe inserts Orthopedic shoe inserts Footmalalignment may be corrected by individually adaptable hardening of theflexible foam insert. Muscle stimulating structures A support structureintegrated into the foam improves posture and movement, relaxes themusculature in the sole of the foot and the calf muscles and improvesthe stability and balance of the wearer. Athlete's shoe inserts A shoeinsert which promotes natural rollover of the foot with a variabledegrees of hardness for loading and unloading and insulating thedifferent regions of the foot. Diabetic adaptive inserts Uniformdistribution of body weight, avoidance of pressure hotspots and pressurerelief attuned to the individual illness- contingent foot situation.Cast shoe foam inserts The foam insert of the cast shoe is partiallyhardened in order to secure and limit the movement of regions of thefoot. Ensures physiologically correct gait. Shoe soles Flip-flopsFootbed adapted to 3-D scan of the foot, for example in the form oflongitudinal arch supports or heel cups. Sports shoes Different degreesof hardness and kinetic structures in the shoe sole for the particularsport-induced load influence on the gait. Cushioning structures inrunning shoes Integrated spring structures support and cushion thestepping motion of the wearer, preferably used for running shoes.Protectors Kinetic protectors The particular body part is protected fromblows or impacts by an insulating foam layer. The movement of the bodypart to be protected is moreover promoted and supported by a specialkinetic structure in the foam. The musculature is likewise supported.Skeletal armoring The protective foam structure is yet furtherreinforced by an additional integrated skeleton. Backpack cushioningelements Pressure distribution and stabilization A support structureinjected into the foam distributes the pressure resulting from theweight of the backpack and the oscillations thereof uniformly over theshoulder region and thus provides additional support and stability.Conforming arm straps A flexible fin-ray structure which wraps aroundthe shoulders when donning the backpack in order to ensure greatersupport. Baby mats Head- and sleeping position-supporting sleep mat Thehead of the baby is supported by a supporting structure in theviscoelastic foam of the sleep mat. Further foam elements support thewaist of the baby in its sleeping position. Breastfeeding pillow Asupporting structure stabilizes the reclining baby while it isbreastfed. Orthopedic Coccyx cushion seat cushions A structure whichunloads the coccyx and promotes straightening of the spine is printedinto any desired foam cushion shape which may appear different to aconventional seat cushion shape. Connecting elements Anchor points forexternal elements Certain locations may be hardened and provide supportfor the mounting of screws or the like. Modular push-fit system Snap-fithooks and eyes may be integrated into the foam block and need only beconnected to one another at the use location. Push-fit adapters forexternal systems Adapters for other systems (threads, snap-fit hooks,bolts) may be printed into the foam. The shape size and spacing thereofmay be adapted to the particular situation. Office chair seat bases Gymball structure An integrated kinetic structure made of a flexiblematerial continually compels the user to balance. The principle is basedon that of sitting on a gym ball which stimulates a particularmusculature. Dynamic seat structure A structure in the foam seat basecompels the body into a minimal level of activity, ensures constantbalancing of the body and promotes straightening of the spine. Transitprotection articles Tailored protective walls in tool case Inserts forcontainers The foam surface made of flexible foam is reinforced in itsprotective function by a hardening structure while no material wasinjected at the locations where an object is to be placed. Recesses intowhich the object may be placed are thus formed and said object thereforeobtains a supporting outer wall present in the foam. Cosmetic spongesBlending sponge with additional grip An imprinted structure makes theblending sponge easier to hold and to guide. Cleaning tools for makeupbrushes An integrated rippled surface allows for excellent cleaning ofmakeup brushes and utensils. Neck-supporting pillows Bathtub neckpillows A neck pillow which is secured to the edge of a bathtub by astiffened reverse side and which supports the neck on the flexible foamwhen reclining by means of its integrated structure. Neck cushion Anintegrated structure ensures optimal support of the head and unloads theneck musculature. Mattresses Mattress with integrated slat frame Astructure injected into the mattress assumes the function of the slatframe. This has the result that the consumer is left with only onemutually optimized element. Mattress with individualized hardnessdistribution Mattresses may be individually adapted to the user withdifferent hardness regions and can thus optimize rest during reclining.Mattress with intelligent protection mechanisms A kinetically activestructure prevents persons from being able to fall out of bed duringsleep. To this end the structure signals to the user that he isapproaching the edge of the bed by raising the edges and thus allows forpeaceful and uninterrupted sleep. Surface haptics Special structuresinjected near to the foam surface elicit pleasant and soothingperceptions and thus offer the user relaxing rest. PillowsIndividualized hardness distribution Pillows may be adapted to the userwith harder and softer areas. Installing of different components is nolonger necessary. IFP may additionally be hardened with a finerresolution. Integrated supporting and unloading functions A particularstructure which prevents head rollover during sleep may be present inthe pillow. This is advantageous especially in the case of neck injuriesin order thus to relax the neck musculature. Cleaning sponges Cleaningsponge with integrated pressure pearls The structure injected into thesponge provides the user with an improved cleaning action. Byapplication of the sponge to an object the protruding pressure pointsensure that soiling can be detached more easily. Cleaning sponge withintegrated bristles Wipe or scrub, small bristles extend depending onthe pressure applied to the sponge. Corner sponge An integratedwedge-shaped structure allows optimal cleaning of right-angled comersand orthogonal intermediate surfaces. Click-in mop The cleaning spongeis provided with integrated click-in elements so that it may beautomatically secured to the end of the cleaning mop. Shoe polish spongeAn integrated structure providing mild resistance promotes distributionof the shoe polish on the shoe surface. Such a combination of a spongeand a brush may be used particularly for suede shoes. Robotic grippersIntegrated gripper structure A structure printed into the foam ensuresthat the foam exerts a gripping movement upon activation of thestructure. This makes it possible to grip and move particularlysensitive and fine objects with a robotic system. Sound absorbers Soundabsorption through a varying foam structure Imprinted structures ensurethat the sound is refracted several times and thus absorbed.Computer-aided injection processes allow for an an optimized absorptionbehavior which is tailored to the particular situation. Self-supportingsound absorber walls Self-supporting sound absorbers made of foam whichare acoustically active and also function as room dividers/walls.Sound-insulated Self-supporting foam stair treads stair treadsSupporting structure integrated into foam for quiet and soft stairtreads which do not transmit impact sound to the supports.Load-distributing structure for foam stair treads In the case of pointloading a special structure distributes the load over the entire foam inorder thus to provide more support and avoid “fallaway” during use. Neckbraces Integrated and individualized reinforcement Patient-tailoredreinforcement of the foam placed around the neck. The structure in thefoam makes it possible to provide more wear comfort and betterstabilization of the neck position. Plaster and rail Integrated andindividualized reinforcement Patient-tailored reinforcement of the foamtied around the affected area. The foam makes it possible to providemore wear comfort and better stabilization. Cushioning pad forIntegrated compulsory operation for fitness apparatus training apparatusOptimized movement control for fitness exercises via injectedstructures. These provide the user with support and prevent theoccurrence of injuries by incorrect performing of movement sequences.Sports mats Load-distributing structure for sports mats In the case ofpoint loading a special structure distributes the load over the entirefoam in order thus to provide more support and avoid “fallaway” duringuse. Apparatus grips Individualized apparatus grips A structureimprinted into the grip which is adapted to the ergonomics of the userallows optimal grip and operation of the particular apparatus. Bicycleseats Adaptive bicycle seat A structure printed into the bicycle seatadapts to the particular posture of the cyclist and thus allowsoptimized support, comfort and maximum force transfer at all times.Tailored bicycle seat A 3-D scan of the cyclist is used to produce asaddle which on account of the integrated structure may be adapted tohis anatomy and ergonomic requirements. Car seats Cornering- andacceleration-adaptive car seats A structure integrated into the seatprovides the driver with increased support and thus provides more safetyin road traffic during occurence of g-forces. Integrated entry and exitaid for car seats A structure integrated into the seat supports thedriver during entry and exit by turning away the driver's seat. Car seatwith integrated frame A structure imprinted into the flexible foamassumes the function of a frame and thus allows for easier and morecost- effective production of car seats. Seating furniture Foam armchairA flexible foam shape contains a sphere cloud structure which forms aseat bowl and backrest as soon as a person sits down on the foam shape.Integrated seating furniture legs A structure projecting from the insideof the from functions as a leg element of a piece of furniture.

The foam body having an internal structure obtainable by a processaccording to the invention, wherein the internal structure comprises afirst polymeric material and the foam body comprises a second polymericmaterial and the material of the internal structure is distinct from thematerial of the foam body has the initial feature that all surfaces ofthe internal structure contact the foam body. This is to be understoodas meaning in particular that there are no cavities between thestructure and the foam body, it being appreciated that this excludescavities present in the foam itself. It is preferable when the contactis a positive contact so that mechanical forces may be more readilytransferred between the foam body and the structure.

It is further provided that the internal structure is a spring having aloading direction. The loading direction of the spring is the directionupon which the design of the spring is based. Upon loading of the foambody at a location at which the internal structure is present and uponloading along the loading direction of the internal structure thedetermined compressive strength (40% compression, DIN EN ISO3386-1:2010-09) is ≥10% to ≤100% higher than the compressive strength(40% compression, DIN EN ISO 3386-1:2010-09) of the foam body at alocation at which no internal structure is present. According to theapplication the term spring is to be understood as meaning any structurewhich makes it possible to bring about the described change incompressive strength.

The spring integrated into the foam body thus brings about a localelevation in compressive strength compared to regions of the foam bodyin which no spring is integrated and only the foam of the foam body thusdetermines compressive strength. The compressive strength is preferably≥20% to ≤80% higher, more preferably ≥30% to ≤70%.

The presence of the internal structure in the foam body may have asynergistic effect in terms of local compressive strength when thedeformation of the foam is influenced by the internal structure and thedeformation of the structure is influenced by the foam.

In a preferred embodiment of the foam body having an internal structurethe first polymeric material is a polyurethane polymer To avoidrepetition reference is made to the intimations concerning thepolyurethane polymer for the first polymeric material made in connectionwith the process according to the invention.

In a further preferred embodiment of the foam body having an internalstructure the second polymeric material is a polyurethane polymer. Toavoid repetition reference is made to the intimations concerning thepolyurethane polymer for the second polymeric material made inconnection with the process according to the invention.

In a further preferred embodiment of the foam body having an internalstructure the structure is a leaf spring, spiral spring, ellipticalspring, parabolic spring, wave spring, leg spring, rod spring, coilspring or disk spring.

In a further preferred embodiment of the foam body having an internalstructure the internal structure is a plurality of non-interconnectedspherical, elliptical or rod-shaped volumes or a plurality ofinterconnected spherical, elliptical or rod-shaped volumes. The term“spherical” includes deviations from the ideal sphere where the smallestdistance and the largest distance of the surface of the volume from thegeometric midpoint of the volume differ from one another by not morethan 20%, preferably not more than 10%.

Rod-shaped volumes may be interconnected such that two volumes convergeat their ends and thus form a “V-shaped” entity. The angle between thelegs of the “V-shaped” entity may be 5° to 85°, preferably 15 to 60°. Itis also possible for more than two, for example 3 or four, rod-shapedvolumes to converge at a common point. The figure formed may bedescribed such that the rod-shaped volumes form at least some of theedges of a notional pyramid.

Rod-shaped volumes may also be interconnected such that a plurality ofthe volumes forms a network with node points. It is preferable when thenode points are distributed in a periodically repeating manner in atleast a portion of the volume of the body. If the node points aredistributed in a periodically repeating manner in a volume this may bedescribed using the terms of crystallography. The node points may bearranged according to the 14 Bravais lattices: simple cubic (sc),body-centered cubic (bcc), face-centered cubic (fcc), simple tetragonal,body-centered tetragonal, simple orthorhombic, base-centeredorthorhombic, body-centered orthorhombic, face-centered orthorhombic,simple hexagonal, rhombohedral, simple monoclinic, base-centeredmonoclinic and triclinic. The cubic lattices sc, fee and bec arepreferred.

Persisting with the crystallographic perspective the number ofrod-shaped volumes by means of which one node point is connected toother node points may be regarded as the coordination number of the nodepoint. The average number of rod-shaped volumes that emanate from thenode points may be ≥4 to ≤12 but it is also possible to achievecoordination numbers that are unusual or impossible in crystallography.

The present invention is more particularly elucidated using the figureswhich follow and with reference to particular embodiments without,however, being limited thereto.

FIG. 1 shows an internal structure to be formed in the foam body

FIG. 2 shows a step in the process according to the invention

FIG. 3 shows a further step in the process according to the invention

FIG. 4 shows a further step in the process according to the invention

FIG. 5-23 b show foam bodies according to the invention

Step (I) of the process according to the invention comprises selectingan internal structure to be formed in the foam body. This selecting isadvantageously carried out in a CAD program which provides athree-dimensional model of the structure and in this three-dimensionalmodel subdivides the structure into individual volume elements.

One example of such a structure to be formed in the foam body is shownin FIG. 1. What is concerned here is a coil spring 100 which is shown incross section. The coil spring 100 further comprises a top plate 110 anda base plate 140. Cross sections 120 and segments 130 of the springdisposed behind the sectional plane define the coil spring 100.

Such coil springs 100 may be provided in mattresses or cushions forexample, so that local regions having an elevated compressive strengthare formed. In connection with placement in a mattress or a cushion thetop plate 110 and the bottom plate 140 are used for better introductionof compression forces into the spring 100.

FIG. 2 is a schematic diagram of step III) of the process according tothe invention. Into the foam body 10, using an injection means in theform of a cannula 20, a predetermined amount of material 30 is injectedinto the foam body 10. In the case of a thermoplastic polymer a melt ofthe polymer is injected. However, it is also possible to employmulticomponent systems in which a reaction mixture reacts to afford thedesired polymeric material. The reaction mixture may be injected throughthe cannula 20 in ready-mixed form or else be mixed only in the foambody 10 through use of a cannula having a plurality of conduits forexample.

In a particular embodiment the reactive material may also be injectedseparately (even geometrically from different spatial directions) viatwo independent injection means such as cannulas for example and thencombined in the target location. However it is also possible that asingle injection means is provided for combining different streams ofthe components of a reactive material in the target location.

The injected quantity of material 30 is supported by the surroundingfoam of the foam body 10 and can therefore remain in the locationintended therefor. The injected quantity of material 30 corresponds,also in terms of its situation in the foam body 10, to a volume elementof the internal structure to be formed.

Other options for performing step III) are shown in FIGS. 3 and 4. Thesituation according to FIG. 3 follows from the situation according toFIG. 2. After injection of the material 30 in FIG. 2 the cannula 20 wasremoved from the foam body 10 and reinserted at another location.Subsequently, further material 31 is injected at a further predeterminedlocation which in this case is adjacent to the previously injectedmaterial 30.

The situation shown in FIG. 4 follows from the situation shown in FIG.3. After injection of the material 31 the cannula 20 was removed fromthe foam body 10. The cannula 20 is subsequently introduced at a newlocation and material 32 is injected.

FIG. 5 shows a foam body having an internal structure as the finaloutcome of the process according to the invention in a cross sectionalview. The spring 100 having a top plate 110 and a base plate 140 whichwas selected as the internal structure and is shown in FIG. 1 isembedded in the foam body 10. The foam of the foam body 10 penetratesthe spring, i.e. the volume formed by the windings of the spring whosecross sectional areas are labeled with reference numeral 120 is not acavity but rather is filled by foam. This is easy to implement via theprocess according to the invention since the internal structure isconstructed in existing foam.

For better understanding FIG. 6 shows the same cross sectional view asFIG. 5 with the exception that therein the segments 130 of the springpresent in the foam and disposed behind the sectional plane are shownwith dashed lines.

In a preferred embodiment of the process the injected melts or theinjected reaction mixtures at least partially join with one another toafford a common volume element in two consecutive steps III). This isshown in FIG. 3. The introduced material 30 and 31 combines to afford acommon volume so that one-piece structures or structure sections mayalso be constructed. In the case of injection of a polymer melt the factthat the foam body 10 acts as a thermal insulation means may beutilized. This facilitates the coalescing of the polymer melt injectedin the individual injection steps.

A foam body according to the invention shall be further elucidated withreference to to FIGS. 1, 5 and 6. The foam body 10 having an internalstructure 100 obtainable by a process according to the invention,wherein the internal structure 100 comprises a first polymeric materialand the foam body 10 comprises a second polymeric material and thematerial of the internal structure 100 is distinct from the material ofthe foam body 10 has the initial feature that all surfaces of theinternal structure 100 contact the foam body 10. This is to beunderstood as meaning in particular that there are no cavities betweenthe structure 100 and the foam body 10, it being appreciated that thisexcludes cavities present in the foam itself. It is preferable when thecontact is a positive contact so that mechanical forces may be morereadily transferred between the foam body 10 and the structure 100.

It is further provided that the internal structure 100 is a springhaving a loading direction. The loading direction of the spring is thedirection upon which the design of the spring is based. Thus the springshown in FIG. 1 is subjected to tensile or compressive load along thedotdashed line. Upon loading of the foam body 10 at a location at whichthe internal structure 100 is present and upon loading along the loadingdirection of the internal structure the determined compressive strength(40% compression, DIN EN ISO 3386-1:2010-09) is ≥10% to ≤10 000% higherthan the compressive strength (40% compression, DIN EN ISO3386-1:2010-09) of the foam body 10 at a location at which no internalstructure 100 is present.

The spring integrated into the foam body 10 thus brings about a localincrease in compressive strength compared to regions of the foam body inwhich no spring is integrated and only the foam of the foam body thusdetermines compressive strength. The compressive strength is preferably≥20% to ≤80% higher, more preferably ≥30% to ≤70%.

The presence of the internal structure 100 in the foam body 10 may havea synergistic effect in terms of local compressive strength when thedeformation of the foam is influenced by the internal structure 100 andthe deformation of the structure 100 is influenced by the foam. In thesimplest case, as shown in FIGS. 5 and 6, the foam present between thesegments 130 of the spring can have the effect that the spring alreadyachieves its maximum possible compression at a lower compression travel.

FIG. 7 to FIG. 23b show examples of foam bodies according to theinvention in which the internal structure is a plurality ofnon-interconnected spherical or rod-shaped volumes or a plurality ofinterconnected spherical or rod-shaped volumes.

FIG. 7 shows a foam body 10 having internal structures in the form ofnon-interconnected spherical volumes 200. The material of the foam body10 may comprise a polyurethane foam for example and the material of thevolumes 200 a thermosetting or elastomeric polyurethane or epoxy resinfor example. Volumes 200 present in the foam body 10 shown here arepositioned in a plane just below the surface of the foam body 10 so thatan aesthetic or functional influencing of the surface may be achieved.

FIGS. 8a and 8b show foam bodies 10 having internal structures in theform of non-interconnected spherical volumes 200. The material of thefoam bodies 10 may comprise a polyurethane foam for example and thematerial of the volumes 200 a thermosetting or elastomeric polyurethaneor epoxy resin for example. Volumes 200 present in the foam bodies 10shown here are positioned in the volume of the foam bodies 10 randomly(FIG. 8a ) or in a cubic grid (FIG. 8b ). One application for foambodies 10 functionalized in such a way is in acoustic absorbtionelements.

FIG. 9 shows a foam body 10 having an internal structure in the form ofinterconnected nominally spherical volumes 200. The material of the foambody 10 may comprise a polyurethane foam for example and the material ofthe volumes 200 a thermosetting or elastomeric polyurethane or epoxyresin for example. Volumes 200 present in the foam body 10 shown hereform a section of a spherical bowl. One application for foam bodies 10functionalized in such a way is in seat cushions having a compressivestrength adjustable via the material and the shape of the connectedvolumes 200.

FIGS. 10a and 10b show foam bodies 10 having internal structures in theform of rod-shaped volumes 300 which are linear (FIG. 10a ) or angled ina V-shape (FIG. 10b ). The material of the foam bodies 10 may comprise apolyurethane foam for example and the material of the volumes 300 athermosetting or elastomeric polyurethane or epoxy resin for example. Intheir longitudinal direction the volumes 300 extend in a direction whichis not parallel with but rather at an angle to a lateral surface of thefoam body 10. The angle may be 40 to 50° for example. In theirlongitudinal direction said volumes in particular do not extendperpendicularly to the surface which is or would be in contact with aperson sitting on the foam bodies 10. This makes it possible to achievedifferent deformation behaviors with respect to the shear forces appliedto this surface. This is shown in the cross sectional views of FIG. 10cand FIG. 10d . The shear load applied in FIG. 10c can push the volumes300 away and thus also compress the foam body 10. By contrast, in FIG.10d the shear load cannot achieve this and the foam body is thereforenot compressed or compressed to a lesser extent than is shown in FIG.10c . One application for foam bodies functionalized in such a way is inseat cushions.

FIGS. 11a and 11b show foam bodies 10 having internal structures in theform of rod-shaped volumes 300 that are non-interconnected but arrangedpairwise in a V-shape with respect to one another. The material of thefoam bodies 10 may comprise a polyurethane foam for example and thematerial of the volumes 300 a thermosetting or elastomeric polyurethaneor epoxy resin for example. The angle in the pairs arranged in a V-shapemay be 40 to 50° for example. Furthermore, the opening of the pairsarranged in a V-shape points in the direction of a lateral surface ofthe foam body 10. This makes it possible to achieve a specificdeformation behavior of the foam body 10 as shown in FIG. 1b . Uponloading, for example by a person sitting on the foam body 10, the foambody 10 is compressed on this side according to the arrangement of theV-shaped pairs. The same effect is also achievable when the volumes 300are in the form of respective continuous angled volumes. One applicationfor foam bodies functionalized in such a way is in seat cushions.

FIG. 12a to FIG. 12c show foam bodies 10 having internal structures inthe form of rod-shaped volumes 300 which are non-interconnected but eachform the edges of a pyramid or a truncated pyramid. The pyramids ortruncated pyramids may have a triangular, square or pentagonal base forexample. The material of the foam bodies 10 may comprise a polyurethanefoam for example and the material of the volumes 300 a thermosetting orelastomeric polyurethane or epoxy resin for example. The angle betweenadjacent pairs of the volumes 300 arranged in a V-shape may be 5° to85°, preferably 15° to 60°, for example. Furthermore, the tip of thepyramids or vuncated pyramids points in the direction of the surfacewhich is or would be in contact with a person sitting on the foam bodies10. This makes it possible to achieve a specific deformation behavior ofthe foam body 10: the greater the angle, the more easily the foam body10 is deformed under load. One application for foam bodiesfunctionalized in such a way is in seat cushions.

FIGS. 13a and 13b show foam bodies 10 having internal structures in theform of rod-shaped volume elements 300 arranged on the lateral surfaceof a notional truncated double cone. The material of the foam bodies 10may comprise a polyurethane foam for example and the material of thevolumes 300 a thermosetting or elastomeric polyurethane or epoxy resinfor example. The inclination angle of the volumes 300 may be 150 to 60for example. Furthermore, one base of the truncated double cones pointsin the direction of the surface which is or would be in contact with aperson sitting on the foam bodies 10. This makes it possible to achievea specific deformation behavior of the foam body 10: compressive loadcauses the foam body 10 to twist as shown in FIG. 13b . One applicationfor foam bodies functionalized in such a way is in seat cushions.

FIG. 14a to FIG. 14c show foam bodies 10 in which internal structuresmade of rod-shaped volume elements 300 serve as frames for reinforcingthe sides of foam bodies 10. The material of the foam bodies 10 maycomprise a polyurethane foam for example and the material of the volumes300 a thermosetting or elastomeric polyurethane or epoxy resin forexample. In the arrangement shown in FIG. 14a the rod-shaped volumeelements 300 are connected to form a rectangular frame. The frameaccording to FIG. 14b is constructed from rod-shaped volume elements300, four of which converge at each branching point. A doubled-upversion of the frame from FIG. 14a is shown in FIG. 14c . The frames arelikewise interconnected via diagonal struts. The reinforcing of the foambody 10 from FIG. 14c against a bending load is shown schematically inFIG. 14d and FIG. 14e . One application for foam bodies functionalizedin such a way is in seat cushions.

FIG. 15 shows a foam body 10 having internal structures in the form ofrod-shaped volumes 300 angled in a V-shape. The material of the foambody 10 may comprise a polyurethane foam for example and the material ofthe volumes 300 a thermosetting or elastomeric polyurethane or epoxyresin for example. The angle may be 40° to 50° for example. Thebisectrix extends parallel to the surface which is or would be incontact with a person sitting on the foam bodies 10. Furthermore, theplane spanning the rod-shaped volumes 300 angled in a V-shape extendsperpendicularly to the surface which is or would be in contact with aperson sitting on the foam bodies 10. One application for foam bodiesfunctionalized in such a way is in seat cushions.

The corner of the volumes angled in a V-shape may also be considered tobe a node point when more than two rod-shaped volumes emanate therefrom.Such an arrangement is shown in FIG. 16a (unloaded state) and FIG. 16b(loaded state). The material of the foam bodies 10 may comprise apolyurethane foam for example and the material of the volumes 300 athermosetting or elastomeric polyurethane or epoxy resin for example.The angle enclosed by two adjacent rod-shaped volumes 300 may be 40° to50° for example. In the foam body 10 the stiffness of the body, forexample during sitting thereupon, may be adjusted via the number ofrod-shaped volumes 300 emanating from one node point. The morerod-shaped volumes converge at one node point, the stiffer the body inthe loading direction. One application for foam bodies functionalized insuch a way is in seat cushions.

FIG. 17 shows a seat cushion such as may be employed as a seat base in avehicle seat. The foam body 10 contains rod-shaped volume elements 300angled in a V-shape in the side bolsters and linear rod-shaped volumeelements in the base section. The material of the foam body 10 maycomprise a polyurethane foam for example and the material of the volumes300 a thermosetting or elastomeric polyurethane or epoxy resin forexample. The linear rod-shaped volume elements act as previouslyelucidated in connection with FIG. 10a /10 c/10 d. The height of thevolume elements 300 angled in a V-shape in the side bolsters increaseswith increasing spacing outward so that a deformation propensitygradient is achieved. The principle of the deformation of the sidebolsters under the influence of the volume elements 300 angled in aV-shape corresponds substantially to the intimations concerning FIG. 11a/b and FIG. 15.

FIG. 18 shows a foam body 10 having internal structures in the form ofroad-shaped volumes 300 which are interconnected and each form the edgesof a pyramid. The pyramids may have a triangular, square or pentagonalbase for example. The material of the foam body 10 may comprise apolyurethane foam for example and the material of the volumes 300 athermosetting or elastomeric polyurethane or epoxy resin for example.The angle between adjacent pairs of the volumes 300 arranged in aV-shape may be 5° to 85°, preferably 15 to 60°, for example.Furthermore, the base of the pyramids points in the direction of thesurface which is or would be in contact with a person sitting on thefoam bodies 10. The length of the angled volume elements 300 increaseswith increasing distance from the center of the foam body so that agradient of deformation propensity is achieved. One application for foambodies functionalized in such a way is in seat cushions.

The same principle of the varying edge length of the pyramids incombination with a variation in the edge angle of the pyramids toinfluence the deformation of the foam body is also implemented in thefoam bodies 10 shown in FIG. 19 and FIG. 20. Shown in each case is afoam body 10 having internal structures in the form of rod-shapedvolumes 300 which are interconnected and each form the edges of apyramid. The pyramids may have a triangular, square or pentagonal basefor example. The material of the foam bodies 10 may comprise apolyurethane foam for example and the material of the volumes 300 athermosetting or elastomeric polyurethane or epoxy resin for example.The angle between adjacent pairs of the volumes 300 arranged in aV-shape may be 5° to 85°, preferably 15° to 60°, for example. Oneapplication for foam bodies functionalized in such a way is in seatcushions.

FIG. 21 shows a foam body 10 having internal structures in the form ofinterconnected rod-shaped volumes 300. The interconnection of the rodshaped volumes 300 may be described as a tree structure. Binary, ternaryand quaternary tree structures are inter alia conceivable. The materialof the foam body 10 may comprise a polyurethane foam for example and thematerial of the volumes 300 a thermosetting or elastomeric polyurethaneor epoxy resin for example. The root of the tree structures preferablyfaces away from the surface which is or would be in contact with aperson sitting on the foam bodies 10. This makes it possible forbranches of the tree structures to absorb stresses and pass these in thedirection of their roots in a controlled manner. One application forfoam bodies functionalized in such a way is in seat cushions.

The compression behavior of the foam bodies is likewise controllable viathe spatial density of node points. FIG. 22a to FIG. 22c show foambodies 10 having ever increasing densities of node points so that theapplied force required for compression is ever increasing. The materialof the foam bodies 10 may comprise a polyurethane foam for example andthe material of the interconnected rod-shaped volumes 300 athermosetting or elastomeric polyurethane or epoxy resin for example.One application for foam bodies functionalized in such a way is in seatcushions.

Similarly to this the compression behavior is also controllable via thethickness of the interconnected rod-shaped volumes 300 as shown in FIG.23a and FIG. 23b . These figures show foam bodies 10 in which whilemaintaining the same spatial density of node points the thickness of theinterconnected rod-shaped volumes 300 is different so that the appliedforce required for compression is ever increasing. The material of thefoam bodies 10 may comprise a polyurethane foam for example and thematerial of the interconnected rod-shaped volumes 300 a thermosetting orelastomeric polyurethane or epoxy resin for example. One application forfoam bodies functionalized in such a way is in seat cushions.

1-15. (canceled)
 16. A foam body having an internal structure, whereinthe internal structure comprises a first polymeric material and whereinthe foam body comprises a second polymeric material and the firstpolymeric material of the internal structure is distinct from the secondpolymeric material of the foam body wherein all surfaces of the internalstructure contact the foam body, and wherein the internal structure is aspring having a loading direction and that upon stressing of the foambody at a location at which the internal structure is present and alonga stressing direction of the internal structure a determined compressivestrength is ≥10% to ≤10,000% higher than a compressive strength of thefoam body at a location at which no internal structure is present asdetermined according to DIN EN ISO 3386-1:2010-09 using 40% compression.17. The foam body having an internal structure of claim 1, wherein thefirst polymer material comprises a plurality of different materials. 18.The foam body having an internal structure of claim 1, wherein the foambody comprises a flexible foam having a compressive strength of ≥10 kPato ≤100 kPa according to DIN EN ISO 3386-1:2010-09 using 40% compressionand a density of ≥10 kg/m³ to ≤100 kg/m³.
 19. The foam body having aninternal structure of claim 1, wherein the second polymeric material isa polyurethane polymer.
 20. The foam body having an internal structureof claim 1, wherein the internal structure alters a deformation behaviorof the foam body under tensile load, compressive load, shear load, or acombination thereof, such that upon deformation under a load a foam bodyvolume element that encompasses the internal structure undergoes achange in volume of ≥10% relative to a volume of the foam body volumeelement that comprises no internal structure.
 21. The foam body havingan internal structure of claim 1, wherein the spring comprises a leafspring, a spiral spring, an elliptical spring, a parabolic spring, awave spring, a leg spring, a rod spring, a coil spring, a disk spring,or a combination thereof.
 22. The foam body having an internal structureof claim 1, wherein the internal structure comprises a plurality ofinternal structure volume elements comprising non-interconnectedspherical volumes, non-interconnected elliptical volumes,non-interconnected rod-shaped volumes, interconnected spherical volumes,interconnected elliptical volumes, interconnected rod-shaped volumes, ora combination thereof.
 23. The foam body having an internal structure ofclaim 7, wherein the plurality of internal structure volume elementshave individual volumes of from ≥10 μL to ≤1000 mL.
 24. The foam bodyhaving an internal structure of claim 1, wherein the first polymericmaterial is a polyurethane polymer.
 25. The foam body having an internalstructure of claim 1, wherein the internal structure is formed in thefoam body by: introducing an injection means at a predetermined locationinside the foam body and injecting via the injection means apredetermined amount of a melt of the first polymeric material orpredetermined amount of a reaction mixture that reacts to afford thefirst polymeric material at the predetermined location, wherein thepredetermined amount corresponds to an internal structure volumeelement, and wherein injecting the predetermined amount destroys and/ordisplaces a portion of the foam body at the predetermined location; andrepeating the introducing step for further predetermined locationsinside the foam body corresponding to further internal structure volumeelements until the internal structure is formed.
 26. The foam bodyhaving an internal structure of claim 10, wherein a plurality ofinjected melts or a plurality of injected reaction mixtures become atleast partially interconnected to afford a common internal structurevolume element.
 27. The foam body having an internal structure of claim10, wherein a plurality of injection means differing in their mechanicalconstruction are employed to introduce the predetermined amount.
 28. Thefoam body having an internal structure of claim 10, wherein a pluralityof introducing steps are performed simultaneously.
 29. The foam bodyhaving an internal structure of claim 10, wherein the injection means isa cannula and the end of the cannula is moved to the predeterminedlocation of the foam body for injection of the predetermined amountwherein an end of the cannula is performed such that the first polymericmaterial already present in the foam body is not contacted by thecannula.
 30. The foam body having an internal structure of claim 10,wherein formation of the internal structure is followed by performanceof a material-removing after treatment step.